As far as the lasting injustice of the Beneš Decrees goes, let me give you an example.
Janos lives and works on the farm his family owned for generations. He is lucky to survive the second world war on the food his land produces. One day the war is over, and the Czechoslovaks come back. There is a new law that declares every Hungarian collectively guilty, all their property is confiscated by the state, and most lose their citizenship too. His farm is given to a Slovak, Pavol, who never had to pay for it. A few years later come the commies, and they collectivise all land, including Janos' farm.
We skip a few decades, it's now the 1990s. The collectivisation process is reversed, and guess who gets the farm back? Not Janos, whose ancestors ploughed that land for centuries, but Pavol. You call that justice? I call it racial discrimination. It's a simple choice - give something back to the original owner, or to some one else by virtue of his ethnicity.
It IS possible to treat minorities like first class citizens. Why does Slovakia continue to treat its Hungarians as second class?